Method and device for the treatment of refuse

ABSTRACT

Method and apparatus for the treatment of refuse. The refuse is heated to a sufficiently high temperature to cause the refuse, even metal included therein, to melt. A molten bath is maintained in such a manner that the combustion products are caused to impinge upon the molten bath so that ash, soot, and other particles become entrained in the bath. The heat resulting from the combustion is used to maintain the bath in a molten state.

United States Patent 1 Ruohola et al.

[ 1 July 24, 1973 METHOD AND DEVICE FOR THE TREATMENT OF REFUSE [75 Ilnventors: Tuomo Ruohola; Pauli Unto J uhani Nyberg; Ero Oskari Joutsen;Kullervo Ennelin, all of Tempere, Finland [73 Assignee: 0y TampellaAB,Tampere, Finland [22] Filed: Mar. 17, 1971 [21] Appl. No.: 125,315

[30 1 Foreign Application Priority Data Mar. 18, 1970 Finland .752/70[52] US. Cl.... 110/8 R, 110/8 A [51] Int. Cl. F23g 5/00 [58] Field ofSearch llO/8 R, 8 E, 18 R,

[56] References Cited UNITED STATES PATENTS 3,616,768 1l/l971 Southwick110/18 2,932,712 4/1960 Levin 110/8 3,344,758 10/1967 Wotschke 110/183,417,717 12/1968 Jacobovici 110/18 3,592,151 7/1971 Webber 110/83,527,178 9/1970 Southwiek 110/8 Primary Examiner-Kenneth W. SpragueAtl0rney-Hall, Pollock & -Vande Sande [57] ABSTRACT Method and apparatusfor the treatment of refuse. The refuse is heated to a sufficiently hightemperature to cause the refuse, even metal included therein, to melt. Amolten bath is maintained in such a manner that the combustion productsare caused to impinge upon the molten bath so that ash,-soot, and otherparticles become entrained in the bath. The heat resulting from thecombustion is used to maintain the bath in a molten state.

14 Claims, 1 Drawing Figure l 1 METHOD AND DEVICE FOR THE TREATMENT OFREFUSE The present invention relates to a method for the treatment ofrefuse by combustion.

The proper disposal of ashes of burnt refuse causes problems which arealmost as severe as those resulting from the dumping of refuse ondumping grounds. In fact, the dissolving of materials from ashes intothe ground water may constitute an even more serious problem. Anotherdrawback of the combustion of refuse is that non-combustible or poorlyburning refuse is treatable in this way.

To remove these drawbacks it has been suggested that the temperature ofthe burning refuse so that the non-combustible wastes, e.g., of metal,as well as ashes, will melt. Various drawbacks have, however, appearedin the devices constructed in accordance with this principleas pointedout, for example, in the publication Brennstoff-Warme-Kraft (1968), no.5. This publication also contains a description of an improved devicewherein at a certain point, the temperature is raised to a value as highas l,400 l,700 C. The slag, which becomes liquid at this temperature, isdelivered to a water bath where very finely divided, sterile granulateis formed. This can be made use as a soil filling without risk ofcontamination of the ground water.

The present invention comprises an improvement over the prior artdescribed above, and the purpose of the invention is to provide a methodand equipment wherein refuse is treated by combustion and thetemperature thereof is elevated to a level where the refuse and/or itscombustion products will melt. A special and new characteristic of themethod in accordance with the invention is that the melts will becomejoined with each other and are maintained as a molten bath by theintroduction of heat. Various considerable advantages are obtainedhereby in comparison with the prior art described above.

An important advantage obtained by the method in accordance with theinvention consists of the fact that in the molten bath even those wasteswhich create the most difficulty are destroyed and even those materialswhich are not readily melted are heated sufficiently to melt completely.This is particularly important in grateless refuse burning furnaces, inwhich the article is dropped from above and only a short time isprovided for proper burning. Furthermore, there are many different kindsof waste materials and it is therefore difficult to maintain conditionsin the burning zone that are suitable for all different wastes. With themethod in accordance with the invention, this is not necessary as thewaste which passes through the burning zone even at high speed entersthemolten bath and will there be subjected to so high a temperature that itwill be melted and incorporated in the molten bath.

From time to time an appropriate quantity of melt is removed from thebath, and this melt is allowed to cool. In this way, large solid piecesare formed, the removal of which is much easier than the removal ofrefuse in the form of small grains or flakes. Such pieces, cast into biglumps, can be used for numerous purposes in addition to its use as soilfilling when it is in the form of loose grains. One can even say that bythe method in accordance with the invention, as a result of thedestroying of waste materials, so valuable a product is obtained thatthe apparatus in accordance with the invention can as well be regardedas an apparatus for making this product than as an apparatus for thedestroying of wastes. In respect to the apparatus, this is of greatimportance as it will be economically profitable to provide theapparatus with control and regulating devices for automatic operation.

Other advantages, specialities and details of the invention aredescribed in the following with reference to the enclosed DRAWING whichschematically shows a vertical section of the device for the handling ofrefuse in accordance with an embodiment of the. invention.

On the left in the DRAWING is shown a chute 1, into which the refuse isintroduced as indicated by arrows. The refuse is moved through the chuteby any means such as a screw 2. By altering the rotational velocity ofthe rate of screw, the feeding can be regulated. Combustion air isdelivered into the furnace 3 fromwall openings 4 which are connectedwith the annular ring 5 which communicates with the conduit 6.

In the method according to the invention, it is possible to carry outthe process entirely without supplying extra fuel. This is possibleabove all because the combustion air which is delivered to the furnace 3is first preheated to about 500 700 C. Preliminary experiments haveindicated that while the effective heat value of town garbage is todayabout 1,800 3,000 calories/kg, by preheating the combustion air to saidtemperature in accordance with the invention, a burning temperature ofapprox. l,400 C is easily obtained in the furnace 3. This temperature issufficient to melt almost all materials appearing in the refuse, withthe result that the ash will be similar to molten lava.

.In the method according to the invention, the melts are incorporated ina molten bath 7 wherein a troughlike lower member 8. By arranging thislower member 8 to be rotatable about a hinge 9, as indicated by thebroken lines, a desired quantity of the melt can be removed from time totime in the manner indicated by the arrow. It is therefore possible, onthe one hand, to maintain an appropriate amount of melt in the troughand, on the other hand, to produce from this melt, by casting, asubstance that will cool into large pieces in accordance with the moldwhich may be used for casting. r

The pieces cast from the melt can be bar-like, plate- I like or have anyshape whatsoever, depending on the purpose. The cooled pieces are solidand firm in structure, they can be easily worked on and they have, ofcourse, a good resistance to heat. Different building pieces can be madefrom them, as slabs for walls, roofs and floors, building bricks, slabsfor hallways, flue pieces, steps, gravestones and statues, roadcoverings, partition elements etc.

Instead of tipping the trough-like lower part 8 from time to time, themelt 7 can of course be tapped periodically or continuously be a conduitor a channel.

As appears from the drawing, the melt 7 is exposed to the radiation ofthe combustion taking place in the furnace 3 and remains therefore veryhot. This improves the combustion in the space 10 situated above themelt7, into which the preheated combustion air is furthermore deliveredby the conduit 17. A special purpose is to burn the carbon monoxide,appearing at this point, into carbon dioxide. The conduits 6 and 7 arebranched off from a common conduit 11 which receives air from the feedconduit 12, with the air being heated by the heat exchanger 13.Combustion air is delivered into the conduit 12 by a blower (not shown).The heating of the combustion air takes place in the heat exchanger byflue-gases. The flue gases from chamber into an after combustion chamber14, which also receives combustion gases via the conduit from thefurnace 3.

It appears from the foregoing that the method in accordance with theinvention is very uncomplicated and the equipment needed for carryingout the method is inexpensive. The equipment consists of the followingparts: feeding apparatus, furnace, molten bath, aftercombustion furnace,heat exchanger and a channel system. The feeding apparatus 1, 2 pressesand doses the wastes into the furnace chute 3.

The proper combustion takes place by means of preheated air in themiddle part of the furnace 3 or somewhat lower, at the openings 4.Toward the lower part of the furnace 3 an elbow-like directingconfiguration is provided whose purpose is to direct onto the surface ofthe melt 7 the ash, soot and other particles contained in the combustiongases. A step 18 can be provided which holds back or retards such refusepieces which should still be burnt before arriving in the bath 7. Thelocation of the step 18 is preferably such that it is situated on bothsides of the imaginary vertical line passing through the middle of theangle portion 19.

The most essential part of the equipment is the trough part 8 with themolten bath 7. The removal of the melt also takes place here, by tippingor by emptying in a suitable manner. The admission of combustion airfrom the conduit 17 causes the combustible gas parts, remaining in theflue-gases, such as for example carbon monoxide, to be burnt. In theafter-combustion chamber 14 gases are burnt tangentially by means of theadditional air admitted by the conduit 16 and by means of the dampflue-gases admitted through the conduit 15. Such after-combustionchamber can also be provided with heat recovery, whereby the temperatureof the combustion gases is decreased so much that the preheating of thecombustion air can be easily carried out. The preheating device 13 ofthe combustion air is situated immediately behind the after-combustionchamber 14. The after-treatment of gases, heat recovery, cooling,purification etc. is carried out on the basis of ordinary technique.Thus, the gases must, for example, in many cases be washed due to theevaporated salts. Of essential importance in the equipment in accordancewith the invention is furthermore the channel system 4,5,6,l7,1l,12,15and 16, the importance of which has already been described above.

We claim:

1. A method for the combustion of refuse comprising the steps of:

burning the refuse in the presence of heated air as it falls freelyunder the influence of gravity through a combustion chamber at atemperature sufficiently high to reduce to a molten state the metal andglass constituents which may be present in the refuse,

maintaining a molten pool of the metal and glass constituents of therefuse,

collecting at the bottom of the combustion chamber at a location remotefrom the molten pool any unburned portions of the refuse,

conveying the combustion products of the burning step and also anyunburned portions of the refuse to the surface of a molten pool so as toincorporate within said pool the ash and soot resulting from the burningstep and as well the unburned portions of refuse, and

maintaining said pool in a molten state by the combustion gases whichflow above the molten pool.

2. The method of claim 1 in which the sole source of heat for the methodis provided by the burning of the refuse.

3. The method of claim 1 wherein additional air is introduced over themolten bath.

4. The method of claim 3 wherein both the additional air introduced overthe molten bath and also the heated air introduced in the burning stepare heated by the combustion gases which in turn are heated by themolten bath.

5. The method of claim 1 wherein the combustion products are conveyedlaterally across the surface of the molten pool.

6. The method of claim 1 wherein during the burning step the temperaturewithin the furnace is maintained at about a minimum of 1,400 C.

7. Apparatus for the burning of refuse comprising in combination,

a vertical combustion chamber having means for the introduction ofrefuse into a top portion thereof and constructed to permit the refuseto fall freely vertically therethrough,

means for containing a molten pool of refuse and of the combustionbyproducts from said combustion chamber,

said containing means being laterally offset from said combustionchamber and communicating with the bottom of said combustion chamber viameans including a sill portion disposed below the bottom of saidcombustion chamber, and extending substandirection across said moltenbath, and means at least partially surrounding said molten bath toreduce radiation heat losses therefrom.

9. The apparatus of claim 8 wherein said communicating means controlsthe flow of gases and combustion byproducts so as to impinge upon thesurface of said molten bath.

10. The apparatus of claim 7 wherein said containing means comprises atrough-like member.

11. The apparatus of claim 10 wherein said troughlike member is hingedabout a horizontal axis to at times permit the dumping of said moltenbath from said trough.

12. The apparatus of claim 7 which includes an aftercombustion chamberthrough which are conveyed the gases which have been heated by saidmolten bath, heat exchanger means for heating air by the heat containedin the gases passing through said after-combustion chamber, and meansfor conveying at least part of the heated air to the space above saidmolten bath.

combustion chamber through which are conveyed the gases which have beenheated by said molten bath, heat exchanger means connected with theupper end of said after-combustion chamber for heating combustion air,and means for conveying the heated combustion air both to said burningchamber and to said molten bath.

I I 3' ii mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent No. 542 Dated July i973 TUOMO RUOHOLA, PAULI UNTO JUHANI NYBERG'I EERC OSKARI JOUTSEN and KULLERVO ENNELIN It is certified hat: errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

On the Title Page, Section {75] Inventors: The name .of the thirdinventor should be Eero Oskari Jo Signed and sealed this 25th day ofDecember 1973.

(SEALj Attest:

EDWARD M.FLETCHER,JR. RENE TEGTMEYER Attesting Officer V i ActingCommissioner of Patents

1. A method for the combustion of refuse comprising the steps of:burning the refuse in the presence of heated air as it falls freelyunder the influence of gravity through a combustion chamber at atemperature sufficiently high to reduce to a molten state the metal andglass constituents which may be present in the refuse, maintaining amolten pool of the metal and glass constituents of the refuse,collecting at the bottom of the combustion chamber at a location remotefrom the molten pool any unburned portions of the refuse, conveying thecombustion products of the burning step and also any unburned portionsof the refuse to the surface of a molten pool so as to incorporatewithin said pool the ash and soot resulting from the burning step and aswell the unburned portions of refuse, and maintaining said pool in amolten state by the combustion gases which flow above the molten pool.2. The method of claim 1 in which the sole source of heat for the methodis provided by the burning of the refuse.
 3. The method of claim 1wherein additional air is introduced over the molten bath.
 4. The methodof claim 3 wherein both the additional air introduced over the moltenbath and also the heated air introduced in the burning Step are heatedby the combustion gases which in turn are heated by the molten bath. 5.The method of claim 1 wherein the combustion products are conveyedlaterally across the surface of the molten pool.
 6. The method of claim1 wherein during the burning step the temperature within the furnace ismaintained at about a minimum of 1,400* C.
 7. Apparatus for the burningof refuse comprising in combination, a vertical combustion chamberhaving means for the introduction of refuse into a top portion thereofand constructed to permit the refuse to fall freely verticallytherethrough, means for containing a molten pool of refuse and of thecombustion byproducts from said combustion chamber, said containingmeans being laterally offset from said combustion chamber andcommunicating with the bottom of said combustion chamber via meansincluding a sill portion disposed below the bottom of said combustionchamber, and extending substantially across the bottom of saidcombustion chamber, said sill portion providing a surface onto which canfall any refuse not fully burnt in said combustion chamber and beingeffective to slow the passage of both unburned refuse and the combustionbyproducts of the refuse burned in said combustion chamber prior topassing into and over the surface of said molten pool.
 8. The apparatusof claim 7 which further includes means for conducting the gasesresulting from the burning in said chamber in a substantially horizontaldirection across said molten bath, and means at least partiallysurrounding said molten bath to reduce radiation heat losses therefrom.9. The apparatus of claim 8 wherein said communicating means controlsthe flow of gases and combustion byproducts so as to impinge upon thesurface of said molten bath.
 10. The apparatus of claim 7 wherein saidcontaining means comprises a trough-like member.
 11. The apparatus ofclaim 10 wherein said trough-like member is hinged about a horizontalaxis to at times permit the dumping of said molten bath from saidtrough.
 12. The apparatus of claim 7 which includes an after-combustionchamber through which are conveyed the gases which have been heated bysaid molten bath, heat exchanger means for heating air by the heatcontained in the gases passing through said after-combustion chamber,and means for conveying at least part of the heated air to the spaceabove said molten bath.
 13. The apparatus of claim 7 which includes anafter-combustion chamber the lower portion of which is in communicationwith the surface of the molten bath, means for introducing airtangentially into the upper portion of said after-combustion chamber,and means for conducting flue gases from the upper part of the burningchamber to said after-combustion chamber.
 14. The apparatus of claim 7which includes an after-combustion chamber through which are conveyedthe gases which have been heated by said molten bath, heat exchangermeans connected with the upper end of said after-combustion chamber forheating combustion air, and means for conveying the heated combustionair both to said burning chamber and to said molten bath.